What is the FE argument on night and day? How can it be night in one place, and day in another place if the Earth is flat?
Since we don't have easy, unrestricted access to the upper atmosphere, there is no definitive answer. The best solution I have seen thus far is, the sun has a limited range of projection and/or there is another object which block its light from half the plane. Call it dark matter...since we have just as much proof for its existence as anyone else does.
Amazing the hoops you FE proponents have to jump through just to get a
single thing to work in your model. In this case, it's sunset/sunrise.
Sadly for them though, once they get that single thing to work, it inevitably breaks something else in the model which then usually requires a terrifically convoluted explanation (shadow object to explain the spotlight sun not being visible at all times) and lots of backtracking on things they supposedly had nailed down (distance to the sun and moon etc). This continues on in an infinite regression for reasons that are obvious.
To address what you're saying, the spotlight hypothesis has been thoroughly debunked and dismissed for various reasons. In fact, I haven't even seen the phrase spotlight sun mentioned for a while in the general/debate forums.
Secondly, there was a thread about the mysterious 'shadow object' that, despite going on for many pages, went precisely nowhere. You may as well invoke a sky god or sky fairies for all the predictive power it has ie. it's an unfalsifiable hypothesis thus it may as well be meaningless drivel.
You know what is a much more elegant, simple and succinct explanation? The Earth is an oblate spheroid which spins on its axis and revolves around the sun. There. Done and dusted; sunsets, sunrises (and everything else) explained. Noticed how I needn't invoke unexplainable and unobservable shadow objects or involve magic and/or the supernatural?